Sticks and stones

Abstract:We hypothesized that an adaptive form of emotion regulation - cognitive reappraisal - would decrease negative emotion and increase support for conflict-resolution policies. In Study 1, Israeli participants were invited to a laboratory session in which they were randomly assigned to either a cognitive-reappraisal condition or a control condition; they were then presented with anger-inducing information related to the Israeli-Palestinian conflict. Participants in the reappraisal condition were more supportive of conciliatory policies and less supportive of aggressive policies compared with participants in the control condition. In Study 2, we replicated these findings in responses to a real political event (the recent Palestinian bid for United Nations recognition). When assessed 1 week after training, participants trained in cognitive reappraisal showed greater support for conciliatory policies and less support for aggressive policies toward Palestinians compared with participants in a control condition. These effects persisted when participants were reassessed 5 months after training, and at both time points, negative emotion mediated the effects of reappraisal.

Abstract:We use Swedish adoption data combined with police register data to study parent-son associations in crime. For adopted sons born in Sweden, we have access to the criminal records of both the adopting and biological parents. This allows us to assess the relative importance of pre-birth factors (genes, prenatal environment and perinatal conditions) and post-birth factors for generating parent-son associations in crime. When considering the extensive margin, we find that pre-birth and post-birth factors are both important determinants of sons' convictions and that mothers and fathers contribute equally through these two channels. At the intensive margin, pre-birth factors still matter, however post-birth factors appear to dominate. In particular, adopting mothers appear to matter most for the probability that sons will be convicted of multiple crimes and/or be sentenced to prison. We find little evidence of interaction effects between biological and adoptive parents' criminal convictions. Having more highly educated adoptive parents, however, does appear to mitigate the impact of biological parents' criminality.

Abstract:Political scientists tend to focus on environmental triggers as the primary precipitating cause for political violence. However, little has been done to explain why certain individuals faced with certain pressures resort to violence, while others confronting the same situation seek out diplomatic and peaceful resolutions to conflict. Here, using two independent samples, we explore the interaction between genetic disposition and violent early life events and their influence on engaging in physical violence. We find that individuals with the low-activity form of monoamine oxidase-A, who are exposed to violence in youth have a greater likelihood of engaging in physical aggression later in adulthood. Our findings hold important implications for the value of environmental intervention in communities besieged by political violence in order to reduce the likelihood of the intergenerational transfer of its propensity.

Abstract:Adolescents are often resistant to interventions that reduce aggression in children. At the same time, they are developing stronger beliefs in the fixed nature of personal characteristics, particularly aggression. The present intervention addressed these beliefs. A randomized field experiment with a diverse sample of Grades 9 and 10 students (ages 14-16, n = 230) tested the impact of a 6-session intervention that taught an incremental theory (a belief in the potential for personal change). Compared to no-treatment and coping skills control groups, the incremental theory group behaved significantly less aggressively and more prosocially 1 month postintervention and exhibited fewer conduct problems 3 months postintervention. The incremental theory and the coping skills interventions also eliminated the association between peer victimization and depressive symptoms.

Abstract:It is well known that violent video games increase aggression, and that stress increases aggression. Many violent video games can be stressful because enemies are trying to kill players. The present study investigates whether violent games increase aggression by inducing stress in players. Stress was measured using cardiac coherence, defined as the synchronization of the rhythm of breathing to the rhythm of the heart. We predicted that cardiac coherence would mediate the link between exposure to violent video games and subsequent aggression. Specifically, we predicted that playing a violent video game would decrease cardiac coherence, and that cardiac coherence, in turn, would correlate negatively with aggression. Participants (N = 77) played a violent or nonviolent video game for 20 min. Cardiac coherence was measured before and during game play. After game play, participants had the opportunity to blast a confederate with loud noise through headphones during a reaction time task. The intensity and duration of noise blasts given to the confederate was used to measure aggression. As expected, violent video game players had lower cardiac coherence levels and higher aggression levels than did nonviolent game players. Cardiac coherence, in turn, was negatively related to aggression. This research offers another possible reason why violent games can increase aggression - by inducing stress. Cardiac coherence can be a useful tool to measure stress induced by violent video games. Cardiac coherence has several desirable methodological features as well: it is noninvasive, stable against environmental disturbances, relatively inexpensive, not subject to demand characteristics, and easy to use.

Abstract:It is well established that violent video games increase aggression. There is stronger evidence of short-term violent video game effects than of long-term effects. The present experiment tests the cumulative long-term effects of violent video games on hostile expectations and aggressive behavior over three consecutive days. Participants (N = 70) played violent or nonviolent video games 20 minutes a day for three consecutive days. After gameplay, participants could blast a confederate with loud unpleasant noise through headphones (the aggression measure). As a potential causal mechanism, we measured hostile expectations. Participants read ambiguous story stems about potential interpersonal conflicts, and listed what they thought the main characters would do or say, think, and feel as the story continued. As expected, aggressive behavior and hostile expectations increased over days for violent game players, but not for nonviolent video game players, and the increase in aggressive behavior was partially due to hostile expectations.

Abstract:The bulk of "neighborhood effects" research examines the impact of neighborhood conditions cross-sectionally. However, it is critical to understand whether the effects of neighborhood context are situational and whether they endure over time. In this study, we take seriously the notion that there are enduring consequences of exposure to deleterious neighborhood conditions. Using a rich set of longitudinal data on adolescents from the Project on Human Development in Chicago Neighborhoods, we estimate the effect of exposure to violence on both internalizing (depression and anxiety) and externalizing problems (aggression). We find that exposure to violence has both an acute and enduring effect on aggression, yet no effect on anxiety-depression, net of individual, family, peer, and neighborhood influences. Part of the enduring effect of violence exposure is explained by changes in social cognitions brought on by the exposure, yet much of the relationship remains to be explained by other causal mechanisms.

Background and objectives: No recent international studies provide evidence about its prevalence, trends, or social determinants of physical fighting in adolescents. We studied cross-national epidemiologic trends over time in the occurrence of frequent physical fighting, demographic variations in reported trends, and national wealth and income inequality as correlates.

Methods: Cross-sectional surveys were administered in school settings in 2002, 2006, and 2010. Participants (N = 493874) included eligible and consenting students aged 11, 13, and 15 years in sampled schools from 30 mainly European and North American countries. Individual measures included engagement in frequent physical fighting, age, gender, participation in multiple risk behaviors, victimization by bullying, and family affluence. Contextual measures included national income inequality, absolute wealth and homicide rates. Temporal measure was survey cycle (year).

Background: Attention deficit-hyperactivity disorder (ADHD) is a common disorder that has been associated with criminal behavior in some studies. Pharmacologic treatment is available for ADHD and may reduce the risk of criminality.

Methods: Using Swedish national registers, we gathered information on 25,656 patients with a diagnosis of ADHD, their pharmacologic treatment, and subsequent criminal convictions in Sweden from 2006 through 2009. We used stratified Cox regression analyses to compare the rate of criminality while the patients were receiving ADHD medication, as compared with the rate for the same patients while not receiving medication.

Results: As compared with nonmedication periods, among patients receiving ADHD medication, there was a significant reduction of 32% in the criminality rate for men (adjusted hazard ratio, 0.68; 95% confidence interval [CI], 0.63 to 0.73) and 41% for women (hazard ratio, 0.59; 95% CI, 0.50 to 0.70). The rate reduction remained between 17% and 46% in sensitivity analyses among men, with factors that included different types of drugs (e.g., stimulant vs. nonstimulant) and outcomes (e.g., type of crime).

Conclusions: Among patients with ADHD, rates of criminality were lower during periods when they were receiving ADHD medication. These findings raise the possibility that the use of medication reduces the risk of criminality among patients with ADHD.

Abstract:Preschool-aged children (M = 42.44 months-old, SD = 8.02) participated in a short-term longitudinal study investigating the effect of educational media exposure on social development (i.e., aggression and prosocial behavior) using multiple informants and methods. As predicted, educational media exposure significantly predicted increases in both observed and teacher reported relational aggression across time. Follow-up analyses showed that educational media exposure also significantly predicted increases in parent reported relational aggression across more than a two year period. Results replicate and extend prior research that has demonstrated links between educational media exposure and relational aggression, but not physical aggression, during early childhood.

Abstract:In this content analysis, we examined violence in Web-based entertainment. YouTube videos (N = 2,520) were collected in 3 different categories: most viewed, top rated, and random, with additional comparisons between amateur and professional content. Frequencies of violent acts and the context of violence (e.g., characteristics of perpetrator and victim, justification, consequences) were compared both between these categories of YouTube videos and with existing research on television violence. The results showed far less violence as a percentage of programming on YouTube than there is on television. Moreover, the violence that was present showed more realistic consequences and more negative context than television violence. Post hoc comparisons illustrated several differences in the presentation of violence between make and category of video.

Abstract:Although testosterone (T) has well known organizational and activational effects on aggression, the relationship between the two is not always clear. The challenge hypothesis addresses this problem by proposing that T will affect aggression only in fitness-enhancing situations. One way to test the challenge hypothesis is to examine the relationship between T and different types of aggression. Chimpanzees, Pan troglodytes, show aggressive behaviours in several contexts and provide an opportunity for such a test. Here we show that urinary T influences a form of male chimpanzee reproductive aggression, territorial boundary patrols. In contrast, T does not affect predatory behaviour, a form of aggression that has no immediate link to male reproduction. While these results are consistent with the challenge hypothesis, our results indicate that male chimpanzees experience a significant drop in urinary T during hunts. Additional analyses reveal that males who share meat with others display this decrease. The reason for this decrement is unclear, but we hypothesize that the relative lack of aggression that results from voluntary sharing episodes and the tolerance engendered by such acts may be contributory factors.

Abstract:Several authors have argued that dehumanization may be the psychological process that underlies people's willingness to torture outgroup members. In the current research, we directly examined this question among Christian participants, with Muslims as the target outgroup. Across two studies, we found that to the extent that Christians dehumanized Muslims, they were more likely to self-report the willingness to torture Muslim prisoners of war. We also found that perceiving Muslims as a threat moderated the relationship between dehumanization and the self-reported proclivity to torture. These findings support the propositions made by previous authors on the role of dehumanization in torture, war and genocide.

Abstract:Previous research has suggested that angry drivers may respond differently to potential hazards. This study replicates and extends these findings. Under simulated driving conditions, two groups of drivers experienced conditions that would either increase angry mood (N = 12; men = 6) or not (control group, N = 12; men = 6). All drivers then performed a neutral drive, during which they encountered a number of traffic events not experienced in the initial drive. These included vehicles emerging from driveways into their path and jaywalking pedestrians. Subjective anger, eye-movement behaviour and driving behaviours (speed and reaction times) were measured as drivers drove. Subjective moods (Profile of Mood States) were assessed before and after each drive. Anger-provoked drivers reported reliably higher increases in angry mood when compared with the control group after the initial drive, and these increases remained stable across the subsequent neutral drive. During the neutral drive, anger-provoked drivers demonstrated evidence of more heuristic style processing of potential hazards, with shorter initial gazes at less apparent hazards and longer latencies to look back at jaywalking pedestrians obscured by parked vehicles. Anger-provoked drivers also took longer to make corrective actions to avoid potential collisions. It is concluded that anger-provoked drivers may initially make more superficial assessments of certain driving situations and consequently underestimate the inherent risk.

Abstract:In 2002 Caspi and colleagues provided the first epidemiological evidence that genotype may moderate individuals' responses to environmental determinants. However, in a correlational study great care must be taken to ensure the proper estimation of the causal relationship. Here a randomized experiment was performed to test the hypothesis that the MAOA gene promoter polymorphism (MAOA-LPR) interacts with environmental adversity in determining aggressive behavior using laboratory analogs of real-life conditions. A sample of fifty-seven Caucasian male students of Catalan and Spanish origin was recruited at the University of Barcelona. Ostracism, or social exclusion, was induced as environmental adversity using the Cyberball software. Laboratory aggression was assessed with the Point Subtraction Aggression Paradigm, which was used as an analog of antisocial behavior. We also measured aggressiveness by means of the reduced version of the Aggression Questionnaire. The MAOA-LPR polymorphism showed a significant effect on the number of aggressive responses in the PSAP (F(1,53)=4.63, p=0.03, partial η2=0.08), as well as social exclusion (F(1,53)=8.03, p=0.01, partial η2=0.13). Most notably, however, we found that the MAOA-LPR polymorphism interacts significantly with social exclusion in order to provoke aggressive behavior (F(1,53)=4.42, p=0.04, partial η2=0.08), remarkably, the low activity allele of the MAOA-LPR polymorphism carriers in the ostracized group show significantly higher aggression scores than the rest. Our results support the notion that gene-environment interactions can be successfully reproduced within a laboratory using analogs and an appropriate design. We provide guidelines to test gene-environment interactions hypotheses under controlled, experimental settings.

About the Author

Kevin Lewis is a columnist for the Ideas section of the Boston Globe. He has degrees in physics and political science from MIT, has studied and taught organizational behavior at UC Berkeley and Duke, and has worked in high-tech business and finance.